org.apache.pig.builtin

Class FunctionWrapperEvalFunc

java.lang.Object

org.apache.pig.EvalFunc<OUT>

org.apache.pig.TypedOutputEvalFunc<OUT>

org.apache.pig.PrimitiveEvalFunc<Object,Object>

org.apache.pig.builtin.FunctionWrapperEvalFunc

public class FunctionWrapperEvalFunc
extends PrimitiveEvalFunc<Object,Object>

EvalFunc that wraps an implementation of the Function interface, which is passed as a String in the constructor. When resolving the Function class, the Pig UDF package import list is used.

The Function must have a default no-arg constructor, which will be used. For Functions that take args in the constructor, initialize the function in a subclass of this one and call super(function).

Example: DEFINE myUdf FunctionWrapperEvalFunc('MyFunction')

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.pig.EvalFunc

EvalFunc.SchemaType

Field Summary

Fields inherited from class org.apache.pig.PrimitiveEvalFunc

inTypeClass

Fields inherited from class org.apache.pig.TypedOutputEvalFunc

outTypeClass

Fields inherited from class org.apache.pig.EvalFunc

log, pigLogger, reporter, returnType

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	FunctionWrapperEvalFunc(ExceptionalFunction function) Determines the input and output types of the Function and initializes the superclass.
protected	FunctionWrapperEvalFunc(com.google.common.base.Function function) Determines the input and output types of the Function and initializes the superclass.
	FunctionWrapperEvalFunc(String functionClassName) Takes the class name of a Function, initializes it using the default constructor and passes it to FunctionWrapperEvalFunc(ExceptionalFunction function).

Method Summary

Modifier and Type	Method and Description
Object	exec(Object input)
protected String	getCounterGroup() Incremented counters will use this as the counter group.

Methods inherited from class org.apache.pig.PrimitiveEvalFunc

exec, getInputTypeClass

Methods inherited from class org.apache.pig.TypedOutputEvalFunc

getOutputTypeClass, getTypeArguments, safeIncrCounter, verifyInput, verifyUdfInput

Methods inherited from class org.apache.pig.EvalFunc

allowCompileTimeCalculation, finish, getArgToFuncMapping, getCacheFiles, getInputSchema, getLoadCaster, getLogger, getPigLogger, getReporter, getReturnType, getSchemaName, getSchemaType, getShipFiles, isAsynchronous, needEndOfAllInputProcessing, outputSchema, progress, setEndOfAllInput, setInputSchema, setPigLogger, setReporter, setUDFContextSignature, warn

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

FunctionWrapperEvalFunc

public FunctionWrapperEvalFunc(String functionClassName)
                        throws ClassNotFoundException,
                               NoSuchMethodException,
                               IllegalAccessException,
                               InstantiationException,
                               IOException

Takes the class name of a Function, initializes it using the default constructor and passes it to FunctionWrapperEvalFunc(ExceptionalFunction function). Functions must implement either com.google.common.base.Function or ExceptionalFunction.

Parameters:

functionClassName - function class to initialize

Throws:

ClassNotFoundException

NoSuchMethodException

IllegalAccessException

InstantiationException

IOException

FunctionWrapperEvalFunc

protected FunctionWrapperEvalFunc(com.google.common.base.Function function)
                           throws IOException,
                                  ClassNotFoundException,
                                  NoSuchMethodException

Determines the input and output types of the Function and initializes the superclass. Subclass and call this constructor if a Function with a non-default constructor is required.

Parameters:

function - Function to be used by the UDF.

Throws:

IOException

ClassNotFoundException

NoSuchMethodException

FunctionWrapperEvalFunc

protected FunctionWrapperEvalFunc(ExceptionalFunction function)
                           throws IOException,
                                  ClassNotFoundException,
                                  NoSuchMethodException

Determines the input and output types of the Function and initializes the superclass. Subclass and call this constructor if a Function with a non-default constructor is required.

Parameters:

function - Function to be used by the UDF.

Throws:

IOException

ClassNotFoundException

NoSuchMethodException

Method Detail

exec

public Object exec(Object input)
            throws IOException

Specified by:

exec in class PrimitiveEvalFunc<Object,Object>

Throws:

IOException

getCounterGroup

protected String getCounterGroup()

Description copied from class: TypedOutputEvalFunc

Incremented counters will use this as the counter group. Typically this works fine, since the subclass name is enough to identify the UDF. In some cases though (i.e. a UDF wrapper that is a facade to a number of different transformation functions), a more specific group name is needed.

Overrides:

getCounterGroup in class TypedOutputEvalFunc<Object>